Conventional display devices that display still images appearing to be animated to a viewer in motion are known. These devices include a series of graduated images—that is, adjacent images that differ slightly and progressively from one image to the next (or groups of identical images that differ groupwise slightly and progressively from one group to the next). The images are arranged in the direction of motion of a viewer, for example along a railroad or sidewalk, such that the images are viewed consecutively. As a viewer moves past these images, they appear animated. The effect is similar to that of a flip-book. A flip book has an image on each page that differs slightly from the one before it and the one after is such that when the pages are flipped, a viewer perceives animation. Traditional linear zoetropes (named from the Greek “zoe-,” life, and “-trope,” cycle; hereafter zoegraphs, from the Greek “graph,” line) have seen widespread commercial implementation.
Existing methods for displaying animated images involves relative motion between the viewer and device are spherical-lens based and cylindrical-lens based systems described in U.S. Pat. No. 2,833,176 and U.S. Pat. No. 3,568,346. These devices (hereafter, lenticular zoegraphs) use lenses placed between viewers and the series of graduated images to cause an animation effect.
Alternatively, zoegraphs can display still images showing different perspectives of the same view using a series of graduated image. For example if a graduated image showed an object viewed from one perspective and each subsequent graduated image showed the same object viewed from how that object would appear to a viewer at the appropriate position to see that graduated image, the viewer would have the effect of seeing that object in three dimensions. This use of a zoegraph may be referred to herein as a “3D Projection” technique. Because the net effect of the 3D Projection technique is to use the same apparatus to show a changing picture to a changing vantage point, for simplicity, the term “motion” may be used in the context of a viewer viewing a zoegraph to describe both the traditional zoegraph effect and the 3D projection effect.
A typical lenticular zoegraph is an apparatus for displaying multiple still images, forming an animated display, to a viewer moving at a substantially known velocity relative to these still images along a known trajectory parallel to these still images. The velocity may be fixed or may vary over the length of the apparatus. A typical lenticular zoegraph includes a backboard, on which are mounted or displayed the still images. A lensboard, consisting of a series of spherical or cylindrical lenses, is positioned parallel to the backboard. Each lens corresponds to one of the images. The whole apparatus is mounted at a viewing distance from the trajectory. In cylindrical lenticular zoegraphs, in order that each image appear in the correct proportion to the viewer, the actual image width is selected to be the product of the desired apparent image width and the quotient of the board-to-board distance and the viewing distance. In spherical lenticular zoegraphs, the actual image height is selected to be the product of the desired apparent image height and the quotient of the board-to-board distance and the viewing distance and the actual image width is selected to be the product of the desired apparent image width and the quotient of the board-to-board distance and the viewing distance.
Lenticular zoegraphs meet a demand to communicate messages to viewers in motion. Messages for which there is demand to communicate to viewers in motion include informative messages about what is ahead in the viewers' paths and advertising. Messages presented to viewers in motion without such devices may not be seen or may appear as an incomprehensible blur. Systems using technologies other than lenticular zoegraphs have met this need—for example, traditional zoegraphs and strobe-based systems, both of which types of systems have enjoyed widespread commercial success. Lenticular zoegraphs offer several advantages in certain environments relative to traditional zoegraphs and strobe-based systems. Nonetheless, lenticular zoegraphs have seen significantly less commercial exploitation than traditional zoegraphs or strobe-based systems. It would be advantageous to create apparatuses that overcome shortcomings of existing zoegraph technologies.
Relative to traditional zoegraphs, lenticular zoegraphs require little or no lighting and show coherent images when the viewer is stationary. Traditional zoegraphs use slits in an otherwise opaque screen between the viewer and series of graduated images to create the animation effect. Blocking the light not passing through these slits decreases the brightness of the animated images, typically by over 90%, requiring additional lighting, which contributes to manufacturing and operating costs and complexity.
Not blocking so much light from the images, enables lenticular zoegraphs to operate with substantially less bright light sources than traditional zoegraphs, including screens such as televisions, computer monitors, projections from image projectors, or other forms or digital or analog images (collectively, “conventional display screens”). Many conventional display screens have two relevant advantages over printed media, which have previously been used in traditional and lenticular zoegraphs. One, the images they display can be transmitted remotely, for example broadcast, like television, or by cable, like a computer monitor. Two, the images they display can be changed without changing any hardware. Therefore, using conventional display screens enables images to be changed remotely and at arbitrary times. In the context of screens with these properties, the term “still images” is to be understood to mean that each particular image does not change during the time the viewer is substantially in front of that particular image.
Relative to strobe-based systems, lenticular zoegraphs require neither synchronization with the viewer's speed or position nor significant, if any, additional lighting or complex lighting systems capable of strobing. Moreover, lenticular zoegraphs create animation at lower speeds and show coherent images to stationary viewers. Strobe-based systems use strobe lights that flash briefly to create the animation effect. The shortness of the flashes requires precise knowledge of the position and speed of the viewer. Typically, strobe-based systems include sensors and timing mechanisms to synchronize the flashing of the strobe lights with the viewer's position and speed. The synchronization and lighting requirements contribute to manufacturing and operating costs and complexity.
Despite being able to operate without some of the constraints of traditional zoegraphs or strobe-based systems, conventional lenticular zoegraphs suffer limitations of their own and have seen little successful commercial implementation relative to zoegraph or strobe-based systems. Drawbacks of conventional lenticular zoegraphs include:                They require placing the images in the focal plane of the lenses. Placing an image in the focal plane of a lens deteriorates the image quality.        As a result, the distance between the lensboard and the backboard must be very precisely maintained or the image will appear distorted, deteriorating the image quality. Current systems provide no inherent way to maintain this distance precisely. In practice, it is very difficult to maintain the images precisely in the focal plane.        Parts of images that are not directly along the axis of the lens appear distorted relative to parts of the image along the axis, deteriorating the image quality.        Replacing the series of images with another series of images requires mechanically removing the series of images to be replaced with a new series of images replacing them. This replacement requires recurring on-site labor, printing of new images, and precision placement of the new series of images, each contributing cost and complexity.        
In view of the foregoing, it is desirable to provide improved systems and methods for displaying images to viewers in motion. It is also desirable to provide new systems and methods for displaying animations to viewers viewing from different perspectives. For example, changing images at a frame rate high enough to create a motion picture effect enables a viewer to view an animation through a lenticular zoegraph with a changing screen displaying the images without moving. This effect can be useful when using a 3D Projection technique to show 3D animations. It is to the provision of such systems and methods that embodiments of the present invention are directed.